In medical, chemical and biological laboratories, microplates are commonly used as a storage medium for various types of samples used for analysis in the laboratory. A laboratory set-up is typically required to handle many samples within a given system. To increase the handling efficiency, a large number of microplates containing samples are stored together for subsequent use in a laboratory procedure. For improved efficiency in the handling of these microplates, a robotic device is typically used with the storage apparatus to remove the microplates from the store for processing and/or replace them after processing. There arc several methods and apparatus currently available that are capable of storing microplates in a laboratory set-up.
Conventionally, a cylindrical carousel apparatus has been used to store small samples or cartridges for various applications as seen in U.S. Pat. No. 5,546,315 to Kleinshnitz. Such carousel storage apparatus includes a robotic device used to automate the handling and delivery of the stored samples. The device is situated in the vicinity of the rotating carousel and utilizes at least two degrees of motion to pick a sample from the carousel for delivery to another instrument within the system. One degree of motion (typically horizontal) is necessary to approach and retreat from the carousel and the other degree of motion (typically vertical) is provided to access samples above or below one another. A third degree of motion is accomplished by the rotation of the carousel.
One of the disadvantages of these existing carousel storage apparatus is that unless the destination for the placement of the sample is directly above or below the carousel, an additional degree of motion is necessary for the robotic device. This is typically rotational about an axis parallel to the central axis of the carousel, and is necessary where delivery to an instrument requires a horizontal translation. PCT publication WO 99/01894 to Zinger et al. discloses a more complex robotic device needed to acquire the third degree of motion. These required movements of the robotic device create a designated area within the system where the robotic arm can operate without interference. In a laboratory setting where it can be vital for instruments to be in close proximity, the additional space required by the delivery system is undesirable.
Furthermore another disadvantage of the existing carousel storage apparatus is that due to tie rotational movement of the carousel necessary to give the robot arm access to the array of items, it is required that a shelf structure is present to secure the items being stored and prevent these items from shifting or sliding due to the carousel's numerous movements. This can require locking mechanisms to ensure the secure placement of a sample. In addition, the rotational movement of the carousel requires that the carousel include a motor to create the rotational movement and a controller for this motor. This added complexity is in addition to the functionality required by the robotic device.
The samples stored within a cylindrical carousel tend to be spaced evenly about the circumference of the apparatus at each layer provided by the structure. Because of the finite size of the samples, the samples are distributed about the circumference and this creates an area within the core of the apparatus that becomes unused space. In a laboratory setting where space can become a vital asset, the unused space within the core increases the footprint of the storage device and utilizes additional space.
An attempt to use the unoccupied central core of a cylindrical storage apparatus as seen in U.S. Pat. No. 5,733,024 to Slocum et al., requires that the storage apparatus be of a half-cylinder rather than a complete cylinder. The storage apparatus allows a robotic device to be placed within the core of the half-cylinder, however part of the main structure must be removed to permit the delivery of the sample from the storage apparatus to another part of the system.
This arrangement not only limits the storage capacity but also delivery by the robotic device is limited to a single aperture and thus a single site in which it can deliver the desired sample to another instrument in the system.
It is thus an object of this invention to obviate or mitigate at least one of the above mentioned disadvantages.